Stewart Cink made history after moving five shots clear in his pursuit of a third RBC Heritage title. (More Sports News)
Two-time champion Cink carded a second successive 63 to set the 36-hole record at Harbour Town on Friday.
Cink sits at 16-under 126, five strokes ahead of Corey Conners – eclipsing the previous best midway score of 129 set by Phil Mickelson (2002) and Jack Nicklaus (1975).
The 47-year-old Cink also became the oldest player to hole the 36-hole lead at the RBC Heritage – his last 36-hole lead on the PGA Tour was at the 2008 Travelers Championship.
Cink has catapulted himself to the top of the leaderboard alongside his son and caddie, Reagan.
"He's not just my son caddying, he's a professional caddie doing an excellent job," he said. "He could caddie for any player in the world right now."
Canadian Conners posted a seven-under-par 64 to be outright second, a stroke ahead of Emiliano Grillo (64) heading into the weekend, while overnight leader Cameron Smith (71) fell seven shots behind.
"I think the golfing gods got a few back on me today," Australian Smith said.
Masters runner-up Will Zalatoris shot a four-under-par 67 to be tied for 11th position, nine strokes adrift of Cink.
World number one Dustin Johnson climbed 27th spots following a second-round 67 as he sits 11 shots back.
Defending champion Webb Simpson, meanwhile, is three under at the half-way stage after his 68.
